Dams, sand mining and pollution endanger 'Tiger of Cauvery'

CHENNAI: The name tells it all, the Tiger of Cauvery, referring to freshwater fish hump-backed mahseer restricted to the river system which can reach a length of 150 cm and weigh up to 90 kg. The mega-sized freshwater fish cries for a sanctuary to protect the species, as their habitat is threatened by reservoirs, sand mining and pollution.

If there can be sanctuaries to protect animals like Tigers, elephants, and birds, there could be one for freshwater fish too. Olive ridleys and dugongs enjoy some protection in protected marine zones, but not for the Tiger of Cauvery. Freshwater fishes like hump-backed mahseer that are restricted to the local river systems have been awaiting attention for a long. Hump-backed mahseer is categorised as critically endangered (red list) by the IUCN (International Union for Conservation of Nature).

Dr Vidyadhar Atkore, a freshwater ecologist with Salim Ali Centre for Ornithology and Natural History (SACON) in Coimbatore, said that mega fish like hump-backed mahseers are migratory and they travel upstream for breeding and feeding.

“But, freshwater ecosystems have been damaged due to dams, extraction of water and sand mining. This affects the free flow of the rivers and the migration of fish. Fragmentation of the river impacts their ecology,” he added.

Despite being put under lots of stress due to irrigation, hydropower generation and sand mining, research on the mega fish and their migration pattern are few and far between. Scientific documentation of migratory fishes in river systems is required for their conservation.

“In countries like the USA and Canada, large dams have been demolished to allow migration of fish species like salmon. In India, there are several hydropower plants and many dams that are more than 50 years old and are now defunct and can be removed. While implementing developmental projects, conservation should be at the top of the agenda,” say conservationists.Dr Atkore opined that the governments should conduct proper surveys at the proposed sites before constructing dams and critical fish species in the rivers should be documented. Moreover, dams should not be built in the habitats of critical species such as hump-backed mahseer.

“Agricultural pesticides and insecticides that seep into the river system are also affecting the river ecosystems. Around 80 per cent of freshwater is being used for agriculture alone in the country, “ he added.

Emphasizing the need to create awareness among the public about the migratory nature of fishes, Dr Vidyadhar Atkore urged to protect the big fishes of rivers like the Tigers, by announcing them as protected species.